Craniofacial abnormalities in Japanese patients with severe obstructive sleep apnoea syndrome

Objective: To clarify that factors besides obesity play an important role in the development of obstructive sleep apnoea syndrome (OSAS) in Japanese patients, we compared craniofacial structures in patients with severe OSAS with those of normal controls.
Methodology: The craniofacial structures of 60 Japanese patients with severe OSAS and 30 normal controls were evaluated using standard cephalometric analysis. Patients were stratified according to body mass index (BMI): non-obese, BMI < 25; moderately obese, BMI = 25–30, severely obese, BMI > 30.
Results: The SNA (sella to nasion to subspinale angle) was significantly smaller in the patient groups than in the controls. The SNB (sella to nasion to supramentale angle) and NSBa (cranial base flexure) were significantly smaller in the non-obese and moderately obese patients than in controls. The MP-H (distance from the mandibular plane to the hyoid bone) and the PNS-P (distance from the posterior nasal spine to the tip of the soft palate) were significantly longer in the patient groups than in the controls. The PNS-P was significantly longer in the severely obese patients than in the non-obese patients.
Conclusions: Japanese patients with severe OSAS have enlargement of the soft tissues and palate as well as craniofacial bony structural abnormalities. This is particularly apparent in non-obese patients.     

Obesity and craniofacial structure as risk factors for obstructive sleep apnoea: impact of ethnicity

OSA is the result of structural and functional abnormalities that promote the repetitive collapse of the upper airway during sleep. This common disorder is estimated to occur in approximately 4% of men and 2% of women, with prevalence studies from North America, Australia, Europe and Asia indicating that occurrence is relatively similar across the globe. Anatomical factors, such as obesity and craniofacial morphology, are key determinants of the predisposition to airway collapse; however, their relative importance for OSA risk likely varies between ethnicities. Direct inter-ethnic studies comparing craniofacial phenotypes in OSA are limited. However, available data suggest that Asian OSA populations primarily display features of craniofacial skeletal restriction, African Americans display more obesity and enlarged upper airway soft tissues, while Caucasians show evidence of both bony and soft tissue abnormalities. Our recent comparison of Chinese and Caucasian OSA patients found for the same degree of OSA severity. Caucasians were more obese, and Chinese had more skeletal restriction. However, the ratio of obesity to craniofacial bony size (or anatomical balance, an important determinant of upper airway volume and OSA risk) was similar between Caucasians and Chinese OSA patients. Ethnicity appears to influence OSA craniofacial phenotype but furthermore the relative contribution of the anatomical factors underlying OSA risk. The skeletal restriction craniofacial phenotype may be particularly vulnerable to increasing obesity rates. Better understanding of craniofacial phenotypes encompassing ethnicity may help improve OSA recognition and treatment; however, further studies are needed to elucidate ethnic differences in OSA anatomical risk factors.     

Weight loss and lifestyle interventions for obstructive sleep apnoea in adults: Systematic review and meta‐analysis

Lifestyle interventions addressing diet, exercise‐training, sleep hygiene, and/or tobacco/alcohol cessation are recommended in the management of obstructive sleep apnoea (OSA). Yet their effectiveness on this condition still requires further research. This systematic review and meta‐analysis was aimed at establishing (a) the effectiveness of lifestyle interventions on apnoea‐hypopnoea index (AHI), oxygen desaturation index (ODI), excessive daytime sleepiness (EDS), and secondary OSA measures among adults, and (b) which intervention characteristics may drive the greatest improvements. A systematic search of studies was conducted using CINAHL, ProQuest, Psicodoc, Scopus, and Web of Science, from inception to April 2018. Standardized mean differences were calculated using the inverse variance method and random‐effects models. The meta‐analyses of 13 randomized controlled trials and 22 uncontrolled before‐and‐after studies (1420 participants) revealed significant reductions on AHI (d = ?0.61 and ?0.46, respectively), ODI (d = ?0.61 and ?0.46) and EDS (d = ?0.41 and ?0.49). Secondary OSA outcomes were also improved after interventions. However, effectiveness of interventions differed depending on their components, OSA severity, and gender. Thus, until future research further supports the differential effectiveness among lifestyle interventions on OSA, those addressing weight loss through diet and exercise‐training may be the most effective treatments for male patients with moderate‐severe OSA.     

A resource of potential drug targets and strategic decision‐making for obstructive sleep apnoea pharmacotherapy

There is currently no pharmacotherapy for obstructive sleep apnoea (OSA) but there is no principled a priori reason why there should not be one. This review identifies a rational decision‐making strategy with the necessary logical underpinnings that any reasonable approach would be expected to navigate to develop a viable pharmacotherapy for OSA. The process first involves phenotyping an individual to quantify and characterize the critical predisposing factor(s) to their OSA pathogenesis and identify, a priori, if the patient is likely to benefit from a pharmacotherapy that targets those factors. We then identify rational strategies to manipulate those critical predisposing factor(s), and the barriers that have to be overcome for success of any OSA pharmacotherapy. A new analysis then identifies candidate drug targets to manipulate the upper airway motor circuitry for OSA pharmacotherapy. The first conclusion is that there are two general pharmacological approaches for OSA treatment that are of the most potential benefit and are practically realistic, one being fairly intuitive but the second perhaps less so. The second conclusion is that after identifying the critical physiological obstacles to OSA pharmacotherapy, there are current therapeutic targets of high interest for future development. The final analysis provides a tabulated resource of ‘druggable’ targets that are relatively restricted to the circuitry controlling the upper airway musculature, with these candidate targets being of high priority for screening and further study. We also emphasize that a pharmacotherapy may not cure OSA per se, but may still be a useful adjunct to improve the effectiveness of, and adherence to, other treatment mainstays.     

Clinical characteristics of Japanese patients with familial obstructive sleep apnoea syndrome

Background and objective: Craniofacial structure and body fat are key factors that predispose to upper airway obstruction while asleep, and these phenotypes can be genetically inherited. Neither the clinical characteristics of familial obstructive sleep apnoea syndrome (OSAS) nor the definitive morphological factors responsible for familial occurrence have been well identified. This study compared the clinical and cephalographic characteristics of Japanese patients with familial OSAS, non‐familial OSAS and healthy controls, to clarify the mechanisms underlying familial OSAS. Methods: The study recruited 28 patients with familial OSAS, comprising 14 index cases and 14 first‐degree relatives affected with OSAS, and compared these with age‐ and sex‐matched patients with non‐familial OSAS (n = 32) and healthy subjects (n = 33). Data on clinical status were collected, including the presence of hypertension, BMI and daytime sleepiness measured on the Epworth sleepiness scale. Respiratory function was evaluated by the AHI, % periods in which SpO₂ fell 90% or below and lowest value of SpO₂ on polysomnograms. Information on the first witnessed age of habitual snoring during sleep was collected via interview with patients and/or their family members. A detailed cephalometric assessment was made of each study subject. Results: Patients with familial OSAS had lower mean BMI than did patients with non‐familial OSAS. The first witnessed age of habitual snoring was younger in the familial cases than the non‐familial cases. Cephalometric variables showed that the posterior airway space and the distance between the gonion and the gnathion were significantly smaller in the familial group than in the other two groups. Conclusions: Familial OSAS occurred at a younger age than non‐familial OSAS due to minor anomalies of craniofacial morphology.     

Neurocognitive impairment in Chinese patients with obstructive sleep apnoea hypopnoea syndrome

Background and objective: Sleep‐disordered breathing is known to be associated with impairment in cognitive function. The aim of this study was to characterize neurocognitive impairment in a cohort of Chinese patients with varying severities of obstructive sleep apnoea hypopnoea syndrome (OSAHS), and to develop a sensitive instrument for routine screening of cognitive impairment. Methods: Eligible patients (n = 394) were categorized into a primary snoring group, and mild, moderate and severe OSAHS groups, based on assessment of AHI. The Montreal Cognitive Assessment (MoCA) and the Mini‐Mental State Examination (MMSE) questionnaires were administered to assess cognitive function, and the correlations between questionnaire scores and clinical and polysomnographic parameters were further evaluated by stepwise multivariate regression. Results: MoCA scores decreased progressively across the spectrum from primary snoring to severe OSAHS. Importantly, mild neurocognitive impairment as defined by a MoCA score <26 was more common in the moderate (38.6%) and severe (41.4%) OSAHS groups than in the mild OSAHS (25.0%) and primary snoring (15.2%) groups. In contrast, MMSE scores were largely normal and comparable among all four groups. Evaluation of MoCA subdomains further revealed selective reduction in memory/delayed recall, visuospatial and executive function, and attention span in the severe OSAHS group compared with the other groups. Stepwise multivariate regression analysis demonstrated that MoCA scores correlated significantly with lowest oxygen saturation (L‐SaO₂) and years of education. Conclusions: Neurocognitive impairment is common in patients with OSAHS. The MoCA is a brief and sensitive tool for the assessment of cognitive impairment in OSAHS patients, whose performance on the MMSE is in the normal range.     

The central motor conductivity of genioglossus in obstructive sleep apnoea

Background and objective: During wakefulness, the electromyography (EMG) activities of upper airway dilator muscles are higher in OSA syndrome (OSAS) patients than those in normal subjects. This is believed to be related to central compensatory mechanisms. This study aimed to assess the central motor conductivity of genioglossus (GG) during wakefulness and to evaluate the compensatory site in OSAS patients. Methods: Twelve OSAS patients and 12 normal subjects were recruited to record motor evoked potential (MEP) of GG to transcranial magnetic stimulation applied at dominant‐sided anterolateral area and GG response to magnetic stimulation at the third cervical level. Stimuli were delivered at the end of expiration and inspiration respectively. The central motor conduction time (CMCT) was calculated by the latency difference between cortical and cervical stimulations. Results: The MEP latency and CMCT of GG in OSAS patients were shorter than those in normal subjects at the end of expiration (MEP latency: 6.08 ± 2.06 ms and 8.24 ± 2.66 ms, respectively, P < 0.05; CMCT: 2.41 ± 1.20 ms and 3.58 ± 1.53 ms, respectively, P < 0.05). However, only in normal subjects, GG MEP latency and CMCT showed significant decrease from the end of expiration to the end of inspiration. GG CMCT of OSAS patients at the end of expiration was closely correlated with AHI (r = ?0.797, P = 0.002), the nadir oxygen saturation (r = 0.76, P = 0.003) and the longest apnoea time (r = ?0.68, P = 0.02). Conclusions: OSAS patients have an increased central motor conductivity of GG than normal subjects. Furthermore, this increased central motor conductivity of GG is related to the severity of OSAS.     

Effects of weight loss on pulmonary function in obese men with obstructive sleep apnoea syndrome

Abstract. The effects of long-term behaviour modification of obesity on pulmonary function was studied in eight men with obstructive sleep apnoea syndrome (initial mean body mass index [BMI] 41.8 kg m^?2) before and after a mean weight loss of 20 ± 7 (SD) kg. Mean arterial Pco₂ fell from 6.3 ± 1.2 to 5.5 ± 0.6 kPa (P < 0.05) and concomitant significant improvements were found in vital capacity, total lung capacity, functional residual capacity and forced expired volume (FEV 1.0). The study suggests that weight loss per se, rather than the method of choice to achieve weight loss, results in clinically significant improvement of pulmonary function in obese men.     

Airline policies for passengers with obstructive sleep apnoea who require in‐flight continuous positive airways pressure

Background and objective: The aim of this study was to investigate the current policies of Australian and New Zealand airlines on the use of in‐flight CPAP by passengers with OSA. Methods: A survey was conducted of 53 commercial airlines servicing international routes. Information was obtained from airline call centres and websites. The policies, approval schemes and costs associated with in‐flight use of CPAP were documented for individual airlines. Results: Of the 53 airlines contacted, 28 (53%) were able to support passengers requiring in‐flight CPAP. All these airlines required passengers to bring their own machines, and allowed the use of battery‐operated machines. Six airlines (21%) allowed passengers to plug their machines into the aircraft power supply. The majority of airlines (19, 68%) did not charge passengers for the use of CPAP, while 9 (32%) were unsure of their charging policies. Many airlines only permitted certain models of CPAP machine or battery types. Conclusions: Many airlines are unaware of CPAP. Those who are, have relatively consistent policies concerning the use of in‐flight CPAP.